Heavy metal pollution in selected upland tributaries of Sri Lanka: comprehension towards the localization of sources of pollution.

This study aimed to assess the heavy metal (HM) profile of the main upland tributaries of three major rivers, the Mahaweli, the Deduru and the Gin Rivers, which are commonly used for urban water supply in Sri Lanka. The HM profiles of arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) were investigated by ICP-MS. Land-use classification was performed to locate the main sources of pollution. Mean pH, TDS and conductivity showed significant inter-site mean differences (p < 0.001). The mean contents of the HMs, considering all rivers, were observed in the order [Hg] > [As] > [Pb] > [Cd] at the sources and [As] > [Hg] > [Pb] > [Cd] at the river mouths. Particularly, in the Mahaweli River, the mean As content was 0.08 ± 0.05 µg·L-1 and showed an increasing trend from the source to the river mouth. In the Deduru River, the mean Hg content was 0.14 ± 0.15 µg·L-1, and of all rivers studied, the highest content of 0.50 ± 0.17 µg·L-1 was recorded. The Gin River showed significant inter-site mean differences (p < 0.05) in [Pb], [As] and [Hg]. In all rivers studied, [As] was significantly higher in water samples collected near agricultural lands and urban areas as compared with the other land-use/cover types, which was further proved by a significant positive correlation (coefficient = 0.479, p = 0.0325). We, therefore, emphasized that HM pollution is more likely due to anthropogenic activities in the upper catchment with less lithogenic contamination. However, national water quality management should be further strengthened and new policy enforcement is emphasized.

Diversity of faecal oxalate-degrading bacteria in black and white South African study groups: insights into understanding the rarity of urolithiasis in the black group.

AIM: To examine whether enhanced diversity or numbers of oxalate-degrading bacteria in the gastrointestinal tracts of black South Africans play a role in determining the rarity of urolithiasis in this group. METHODS AND RESULTS: Fresh faecal samples collected from healthy black and white South African male volunteers were analysed in terms of bacterial oxalate-degrading activity, bacterial diversity and relative species abundance. Varied bacterial populations prepared from samples from the low-risk black group showed a significantly higher level of oxalate degradation. Denaturing gradient gel electrophoresis analyses of Lactobacillus and related spp. and Bifidobacterium spp. 16S rRNA PCR products revealed a significantly higher faecal Lactobacillus diversity for the low-risk black group relative to the higher-risk white group. Quantitative real-time PCR experiments did not show any significant differences between the study groups for Lactobacillus and related spp.. However, Bifidobacterium spp. were present at a significantly higher relative abundance in the black group. Oxalobacter formigenes was present only at very low levels in either group. CONCLUSIONS: The low abundance of O. formigenes and increased diversity and abundance of oxalate-degrading Lactobacillus and Bifidobacterium spp. in the black South African population suggest that these strains rather than O. formigenes may protect this group against calcium oxalate kidney stone disease. SIGNIFICANCE AND IMPACT OF THE STUDY: The South African black population harbours a pool of potential oxalate-degrading lactic acid bacteria, which is more abundant and diverse than that of white South Africans. This may be useful in developing probiotics for calcium oxalate kidney stone prophylaxis.

Enhancement of local superconductivity in ferromagnetic FeCrB metallic glass by Ar+ ion irradiation.

We have reinforced local superconductivity in ferromagnetic Fe(67)Cr(18)B(15) metallic glasses by ion irradiation. Superconductivity in this medium appears due to the presence of large-scale layered clusters of metallic Fe-Cr phase, 150-230 Å in size, with a ferromagnetic (or superparamagnetic) Fe-rich core and nonmagnetic Cr-rich superconducting shell. Here we show that due to the intensification of concentration phase separation in the Fe-Cr clusters under ion (Ar(+)) irradiation, the volume of the superconducting phase increases from the initial 0.4-0.5% up to 7-8%. After irradiation, the resistivity jump Δρ/ρ in the temperature range T=3.1-3.6 K increases ∼14 times, reaching 19%, as compared to 1.36% for the initial sample. In the interval of T=3.1-3.6 K, the rate of resistance change reaches 79% K(-1) for the irradiated sample instead of 3.6% K(-1) for the initial sample. In the same temperature interval, the rate of magnetoresistance change increases from 3% K(-1) for the initial sample up to 70% K(-1) after irradiation.

Calciuria, oxaluria and phosphaturia after ingestion of glucose, xylitol and sorbitol in two population groups with different stone-risk profiles.

The effects of glucose, sorbitol and xylitol ingestion on calciuria, oxaluria and phosphaturia in healthy black and white males on a standardized diet were investigated. After ingestion, they collected urine hourly for 3 h. Glucose decreased phosphaturia in blacks. Sorbitol decreased phosphaturia in both groups and increased oxaluria in whites. Xylitol increased oxaluria in blacks. Decreases in phosphaturia are attributed to penetration by phosphate into cells leading to decreases in phosphatemia and the renal filtered load. We suggest that this mechanism is more sensitive in blacks. We speculate that the increase in oxaluria after sorbitol ingestion occurs via its conversion to glyoxylate and that this pathway may be blocked in blacks. For the increase in oxaluria after xylitol ingestion, it is hypothesized that ketohexokinase and aldolase may be more active in blacks. Our results demonstrate, for the first time, a urinary effect due to sorbitol ingestion and an ethnic dependency of these and other effects.

A genome-wide study of the repressive effects of estrogen receptor beta on estrogen receptor alpha signaling in breast cancer cells.

Transcriptional effects of estrogen result from its activation of two estrogen receptor (ER) isoforms; ERalpha that drives proliferation and ERbeta that is antiproliferative. Expression of ERbeta in xenograft tumors from the T47D breast cancer cell line reduces tumor growth and angiogenesis. If ERbeta can halt tumor growth, its introduction into cancers may be a novel therapeutic approach to the treatment of estrogen-responsive cancers. To assess the complete impact of ERbeta on transcription, we have made a full transcriptome analysis of ERalpha- and ERbeta-mediated gene regulation in T47D cell line with Tet-Off regulated ERbeta expression. Of the 35 000 genes and transcripts analysed, 4.1% (1434) were altered by ERalpha activation. Tet withdrawal and subsequent ERbeta expression inhibited the ERalpha regulation of 998 genes and, in addition, altered expression of 152 non-ERalpha-regulated genes. ERalpha-induced and ERbeta-repressed genes were involved in proliferation, steroid/xenobiotic metabolism and ion transport. The ERbeta repressive effect was further confirmed by proliferation assays, where ERbeta was shown to completely oppose the ERalpha-E2 induced proliferation. Additional analysis of ERbeta with a mutated DNA-binding domain revealed that this mutant, at least for a quantity of genes, antagonizes ERalpha even more strongly than ERbeta wt. From an examination of the genes regulated by ERalpha and ERbeta, we suggest that introduction of ERbeta may be an alternative therapeutic approach to the treatment of certain cancers.

[Vaccine development: strategies for coping with the antigenic diversity of bacteria]. / Les vaccins face à la diversité antigénique des bactéries.

Bacterial pathogens have evolved a whole range of anti-immune strategies to overcome both the innate and acquired immunity of their hosts. These strategies play a crucial role in the capacity of pathogens to trigger disease and also explain why it is so difficult to develop vaccines and to control these microorganisms. One of the main problems is that bacteria are highly antigenically diverse. The vaccination strategies for coping with this variability, which we are starting to understand more fully as a result of sequencing bacterial genomes, consist of using either several variants of one or more proteins capable of inducing protective antibodies, or else proteins (or protein fragments) or epitopes that have been relatively well preserved notably because they are involved in the pathogen's metabolism. The most sophisticated approach calls upon 'pan genomic' inverse vaccinology which compares the protein profiles of a large number of isolates from various strains of a single species in order to reveal the surface-expressed proteins present in all the isolates. Of these proteins, the ones which are expressed when the host is infected are then evaluated in order to determine their capacity to induce a protective immune response. So far this approach has been successful in controlling bacteria in humans and the way is now open for its application in veterinary medicine, thanks to progress with the genomic sequencing of pathogens of veterinary importance.

First Report of Sudden Death Syndrome (Fusarium solani f. sp. glycines) of Soybean in Minnesota.

In August 2002, soybean (Glycine max (L.) Merr.) plants exhibiting foliar and root symptoms typical of sudden death syndrome were observed in Blue Earth and Steele counties in south-central Minnesota. Leaf symptoms ranging from small chlorotic spots to prominent interveinal necrosis were present on soybean plants at the R6 to R7 growth stage. As plants matured, complete defoliation took place with only petioles remaining. Symptomatic plants had necrotic secondary roots, truncated taproots, and discolored cortical tissue at the soil line. Blue sporodochia containing macroconidia were observed on the taproot of affected plants at both locations (3,4). Multiple cultures from both locations were obtained by transferring macroconidia from the sporodochia to potato dextrose agar (PDA) and modified Nash-Snyder Medium (NSM) (3). After 14 days, isolations were made from fungal colonies exhibiting bluish pigmentation and masses of bluish macroconidia (4). The isolates grew slowly, developed a bluish color, and formed sporodochia containing abundant macroconidia on NSM. These isolates were identified as Fusarium solani (Mart.) Sacc. f. sp. glycines based on colony characteristics and morphology of macroconidia (2). Pathogenicity tests were conducted with a single isolate from each location. The isolate from Blue Earth County was inoculated as mycelia in a plug of media onto taproots of plants of susceptible cvs. Williams 82 and Spencer at the V2 growth stage. Chlorotic spots appeared on leaves after 12 days of growth at 22 to 25°C in the greenhouse. Interveinal necrosis appeared after 15 days (4). The isolate from Steele County was used to inoculate the susceptible cv. Great Lakes 3202. Sorghum seed (3 cm3) infested with mycelia of the isolate were placed 2 to 3 cm below soybean seed planted in Cone-Tainers. Noninfested sorghum seed was used as a control. Plants were maintained for 21 days at 22 to 28°C in the greenhouse. Chlorotic spots appeared on leaves of inoculated plants within 21 days after planting followed by the development of interveinal chlorosis and necrosis (1). Molecular analysis further supported the identification of the Steele County isolate as F. solani f. sp. glycines. Polymerase chain reaction with specific primers Fsg1 and Fsg2 of total genomic DNA extracted from the Steele County isolate amplified a 438-bp DNA fragment identical with that extracted from previously identified isolates of F. solani f. sp. glycines (1). In 2002, symptoms of sudden death syndrome were also reported in Olmsted, Freeborn, and Mower counties. Although studies are needed to determine the distribution of sudden death syndrome in the state, the occurrence of the symptoms at multiple locations suggests that F. solani f. sp. glycines is widely distributed in southeast and south-central Minnesota. The counties where sudden death syndrome symptoms were reported are located in the most productive soybean-growing region of Minnesota. Sudden death syndrome could be a serious threat to soybean production in this area since poorly drained, heavy, clay soils are common, and soil temperatures 18°C or less are normal before the end of May. References: (1) S. Li et al. Phytopathology 90:491, 2000. (2) K. W. Roy. Plant Dis. 81:566, 1997. (3) K. W. Roy et al. Plant Dis. 81:1100, 1997. (4) K. W. Roy. Plant Dis. 81:259, 1997.

Anomalous acoustoelectric effect in La0.67Ca0.33MnO3 films.

We have studied the acoustoelectric (AE) effect produced by surface acoustic waves (SAW) in a monolithic layered structure, composed of a piezodielectric LiNbO3 substrate and a La0.67Ca0.33MnO3 film. The experiments unexpectedly revealed in the longitudinal AE effect an anomalous contribution, invariant upon reversal of SAW propagation, which coexists with the ordinary (odd in wave vector) effect. The anomalous effect dominates near the metal-insulator transition, while the ordinary effect prevails at high and low temperatures. We show that the anomalous effect is caused by strong modulation of the film conductivity produced by the SAW elastic deformations.

The influence of a high-oxalate/low-calcium diet on calcium oxalate renal stone risk factors in non-stone-forming black and white South African subjects.

OBJECTIVE: To evaluate the influence of a high-oxalate/low-calcium diet on calcium oxalate stone risk factors in both black South Africans (who are largely immune to kidney stones) and white South Africans (in whom stones are more common). SUBJECTS AND METHODS: Urinary and dietary variables were examined in 11 black and 11 white South African men. None of the subjects had had a kidney stone or any metabolic illness. Their normal domestic food intake was assessed using a semiquantitative food frequency questionnaire. Subjects were given a standardized high-oxalate/low-calcium diet for 3 days; 24-h urine samples were collected before the protocol and during the final day. The samples were analysed using routine modern laboratory techniques. The urine analysis data were used to calculate the Tiselius risk index and the relative urinary supersaturations of calcium oxalate, uric acid and calcium phosphate. RESULTS: Urine analysis showed an intriguing anomaly; black subjects had significantly higher urinary pH and oxalate values than whites (6.50 vs 6.21 and 0.23 vs 0.14 mmol/24 h, respectively), while their urinary citrate was lower (1.47 vs 3.69 mmol/24 h). In addition, the Tiselius risk index and relative supersaturation of calcium oxalate were higher in black subjects. These results are contrary to those which might have been reasonably expected when comparing stone-free and stone-prone groups. After the dietary protocol, the only urinary variable which changed significantly was urinary oxalate, which increased by 57% in whites. CONCLUSION: Factors which are conventionally used to assess stone risk (pH, oxaluria, citraturia, relative supersaturation) are not helpful in identifying why South African blacks are relatively immune to stones. We suggest that relatively lower oxalate absorption rates may be a physiological feature of this racial group.

Antitumor activity of tributyrin in murine melanoma model.

Butyric acid has been known to inhibit growth and to induce differentiation of a variety of tumor cells. Butyrate-treated tumor cells have also been observed to undergo apoptosis. Although butyrate compounds have demonstrated antitumor activity in murine tumor models and have already been admitted to clinical trials in tumor patients, the exact mechanism of their antitumor effects has not been elucidated. The results of our study showed antitumor activity of tributyrin, a butyric acid prodrug, in murine melanoma model and are strongly suggestive that antiangiogenic effects could participate in antitumor effects of butyrate compounds in vivo.

Acoustic characterization of mechanical valve condition and loading.

Both closing dynamics and the mechanical condition of a Björk-Shiley Convexo-Concave (BSCC) valve are significant in assessing the risks of outlet strut fracture. Risk of fracture increases with the presence of a pre-existing fracture in one of the two strut legs and with magnitude and frequency of loading. Recent analyses of in vivo data collected in clinical studies, and in vitro data from a computer-controlled pulse duplicator, indicate that the condition of an outlet strut can be evaluated by non-invasive passive acoustic measurement. The technique utilizes heuristic methods to identify features in time and frequency in the closing sound of BSCC valves. Because of patient-to-patient and beat-to-beat variability in the waveforms of closing sounds, the sound of beats are cross-correlated to identify thirteen characteristic waveform groups that are independent of valve strut condition. The groups are used for subsequent acceptance of each closing event. For each group, a Mahalanobis distance technique is used to identify features in time and frequency that characterize the mechanical condition of the BSCC valve. A Volterra expansion is used to optimize the features. A similar approach, where strain gages supply the measured strut load, is used to identify features associated with valve closing load, and to predict outlet strut forces on a beat-for-beat basis in vitro and in sheep. The characterization is based on a set of acoustic recordings made on patients prior to explant of each valve. Analysis is made using blinded and leave-one-out methods, preventing overlap between the data used in training and that used in testing. Results have demonstrated a sensitivity and specificity to strut fracture of 100 percent on a group of 33 patients for whom gold standard data was available. Analysis of additional blinded data will be useful to further quantify the robustness of the detection method. The relative ease with which data can be collected, and the excellent results, indicate that the method may develop into a practical and effective screen for outlet strut condition.

Filtration leukapheresis: the influence of granulocyte counts upon the donors' yield.

The purpose of this investigation was to determine the influence of granulocyte count on the yield of granulocytes. Healthy adult volunteer donors underwent filtration leukapheresis without premedication. The granulocyte count was measured before and immediately after the procedure. In 73 donors, there was an increase and in 67 donors there was a decrease in the granulocyte counts. In this study of nonmedicated donors those with high initial granulocytes counts and those in which there was a large increase in the postleukapheresis granulocyte counts provided the best yield with the filtration leukapheresis technique.

Superconducting multicontact rotary switch.

A compact mechanical multiposition superconducting switch, suitable for a wide variety of cryoelectronic applications, has been developed. The switch is easy to fabricate in laboratory conditions. Its design is based on principles used in normal rotary switches and offers the same ease in stacking together multiple sections.